The axle housings of vehicles used for earth moving, construction, material handling, mining, and the like, are partially filled with oil or other lubricating fluid (collectively, “oil”) to ease contact between meshing gears contained in the housing. It is desirable to have a film of oil between meshing gear teeth in order to avoid the extreme heat that may otherwise be created in the contact area of the teeth. Such extreme heat causes, between the surfaces of the meshing gear teeth, micro-welding that results in tearing and pitting of the gear teeth and breaking of the teeth due to material fatigue.
Each axle housing typically contains a toothed gear set such as a bevel gear and a pinion gear. The teeth of the smaller dimensioned pinion gear mesh with the teeth of the bevel gear. Generally, an output shaft from the vehicle transmission provides power to rotate the pinion gear. The rotating and meshing of the pinion gear teeth with the bevel gear teeth drives the bevel gear and transfers power, through the rotating bevel gear, to the wheels of the vehicle. The gear ratio of the pinion gear to the bevel gear typically creates a reduction of the input speed from the transmission and an increase in the torque applied to the wheels.
Generally, the axle housing is filled with enough oil to ensure that gear teeth, including those of the bevel and pinion gears, are lubricated. Thus, a larger gear disposed generally vertically within the axle housing (such as the bevel gear), which requires a lower fill level of oil in the axle housing, has to rotate through a much deeper oil fill level in order to ensure that other gears (for example, those with smaller diameters, those positioned horizontally) are adequately lubricated. Thus, the oil flow around a large gear, such as the bevel gear, is often turbulent due to the depth of oil in which the gear must rotate. This turbulence may be compounded by the meshing of gears, such as the bevel and pinion gears, that have different rotational axes. The input power required to overcome the resistance of the oil to the rotation of the gear(s) may be referred to as “churning loss.” This churning loss results in increased fuel usage as more input power must be applied to make-up for the churning loss.
In addition, the axle housing is filled with enough oil to lubricate componentry disposed in either end of the axle housing (in the legs of axle housing). When the vehicle is operating on an incline, and hence the axle housing is inclined, the oil in the axle housing flows downhill toward the axle housing leg that is lowest on the incline. This flow increases the churning of the oil and decreases the availability of oil for lubrication of the componentry disposed in the leg housing that is higher on the incline. Neither is a beneficial result.
U.S. Pat. No. 3,825,099 (“Hopf”) issued Jul. 23, 1974 is an example of prior art related to oil associated with bevel gears in axle drives. FIG. 1 of Hopf discloses a lubrication arrangement in which oil thrown up by the bevel gear is caught by a trough and conducted into collection chambers/pockets. The oil is then gravity fed through a maze of chambers into the differential gear housing that is adjacent to the bevel gear in the center portion of the housing. Disadvantageously, Hopf deposits the oil flowing out of the differential gear housing back into the center portion of the housing in the proximity of the bevel gear. A better design is needed that removes oil from the center housing portion of an axle housing, decreases churning loss and provides a flow of oil to the upper end of the axle housing when the axle housing is inclined.